Crigler-Najjar Syndrome Type I and II
What is Crigler-Najjar Syndrome Type I and II?
Crigler-Najjar syndrome is a rare genetic disorder that causes severe jaundice from birth. The condition happens when your liver cannot process bilirubin properly. Bilirubin is a yellow substance created when your body breaks down old red blood cells.
People with this syndrome lack an enzyme called UDP-glucuronosyltransferase. This enzyme normally converts bilirubin into a form your body can eliminate. Without enough of this enzyme, unconjugated bilirubin builds up in the blood and tissues. This causes the skin and eyes to turn yellow.
There are two types of this condition. Type I is more severe and requires lifelong treatment to prevent brain damage. Type II is milder and often responds to medication. Both types are present from birth and affect fewer than 1 in 1 million people worldwide.
Symptoms
- Severe jaundice that appears within the first few days of life
- Yellow discoloration of the skin and whites of the eyes
- Pale or clay-colored stools
- Dark urine in some cases
- Fatigue and weakness
- Neurological problems if bilirubin levels become dangerously high
- Kernicterus, a type of brain damage from very high bilirubin levels
Most people with Crigler-Najjar syndrome show symptoms immediately after birth. The severity of symptoms depends on which type you have. Type I causes more severe and persistent jaundice than Type II.
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Causes and risk factors
Crigler-Najjar syndrome is caused by mutations in the UGT1A1 gene. This gene provides instructions for making the enzyme that processes bilirubin. The condition follows an autosomal recessive pattern, meaning you need to inherit one mutated gene from each parent to develop the disorder. Parents who carry one copy of the mutation typically show no symptoms.
Type I results from complete absence of the enzyme, while Type II occurs when the enzyme has reduced activity. There are no lifestyle or environmental risk factors for this condition. It is purely genetic and present from birth. Family history is the only known risk factor, particularly in families with consanguinity or blood relation between parents.
How it's diagnosed
Doctors diagnose Crigler-Najjar syndrome through blood tests that measure bilirubin levels. High levels of unconjugated bilirubin with normal liver function tests suggest this condition. A key finding is that urine bilirubin remains negative, which helps distinguish this from other forms of jaundice. Genetic testing confirms the diagnosis by identifying mutations in the UGT1A1 gene.
Rite Aid offers comprehensive blood testing that includes bilirubin markers to help monitor this condition. Testing happens at Quest Diagnostics locations nationwide. Early and regular monitoring helps prevent complications and guides treatment decisions. Your doctor may also order additional specialized tests to determine which type you have.
Treatment options
- Phototherapy using special blue lights to break down bilirubin in the skin
- Phenobarbital medication for Type II to increase enzyme activity
- Liver transplantation for severe Type I cases
- Avoiding triggers like fasting, dehydration, and certain medications
- Regular blood monitoring to track bilirubin levels
- Calcium supplementation to prevent gallstone formation
- Gene therapy, currently in research stages for future treatment
Concerned about Crigler-Najjar Syndrome Type I and II? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Type I is more severe and results from complete absence of the bilirubin-processing enzyme. Type II is milder and involves reduced enzyme activity, usually 10% or less of normal. Type I requires intensive phototherapy and often liver transplant, while Type II typically responds to phenobarbital medication.
The condition follows an autosomal recessive inheritance pattern. This means you must inherit one mutated gene from each parent to develop the syndrome. Parents who carry one copy are called carriers and typically have no symptoms. Each child of two carriers has a 25% chance of having the condition.
No, Crigler-Najjar syndrome is always present from birth. Symptoms typically appear within the first few days of life. If you did not have severe jaundice as a newborn, you do not have this condition. Similar symptoms appearing in adulthood would have a different cause.
Doctors measure total and direct bilirubin levels through blood tests. High unconjugated bilirubin with normal liver enzymes suggests Crigler-Najjar syndrome. Urine bilirubin testing shows negative results, which helps rule out other causes. Genetic testing of the UGT1A1 gene confirms the diagnosis.
People with Type I typically need phototherapy daily for 10 to 12 hours throughout their lives. This prevents bilirubin from reaching dangerous levels that could cause brain damage. Type II patients may need less frequent or no phototherapy depending on their bilirubin levels and response to medication.
Very high bilirubin levels can cause kernicterus, a type of permanent brain damage. This condition affects movement, hearing, vision, and cognitive function. Symptoms include muscle rigidity, abnormal eye movements, and developmental delays. Regular monitoring and treatment prevent this serious complication.
Yes, liver transplant is currently the only cure for Crigler-Najjar Type I. A new liver provides the missing enzyme and restores normal bilirubin processing. Many patients manage well with daily phototherapy, but transplant becomes necessary if phototherapy becomes insufficient or quality of life declines significantly.
Many people with Type II live relatively normal lives with medication and monitoring. Type I requires more intensive daily management with phototherapy. Both types need regular medical care and careful monitoring of bilirubin levels. With proper treatment, people can attend school, work, and participate in most activities.
Certain medications can increase bilirubin levels and should be avoided. These include some antibiotics, pain relievers, and drugs that compete for the same enzyme pathway. Always inform your healthcare providers about your diagnosis before starting new medications. Your doctor can recommend safe alternatives when needed.
While diet does not cure the condition, staying well-hydrated and avoiding fasting helps maintain stable bilirubin levels. Prolonged fasting can increase bilirubin production and worsen jaundice. Eating regular meals and drinking adequate fluids supports overall health. Some patients benefit from calcium supplements to prevent gallstones.